No, you can't; the courts don't issue warrants like that. They'd issue a warrant for that information for one particular patron whom they already had reasonable suspicion of.
If the FBI have a warrant to put a bug on one regular's table, that doesn't seem unreasonable. If the bartender's carefully built the bar so that you can hear every conversation from every table and so the only way you can place a bug is one that would also record everyone else's conversations... yeah, I'd say that's unfortunate (and pretty poor design on the owner's part), but the FBI has the right to place the bug they've got the warrant for, and if there's really no way to do that without it picking up other conversations then too bad.
Only if it is true. He has the data, the article says he has worked with law enforcement before in a kiddie porn case.